Bandwidth Awareness in a Link Aggregation Group

ABSTRACT

In one embodiment, a method includes receiving a request to establish a path for a data stream from the first network apparatus to a second network apparatus, where the request is associated with a requested bandwidth for the data stream, and where the first network apparatus and the second network apparatus are connected by a link aggregation group including a number of physical links, accessing bandwidth information representing a number of remaining bandwidths of the respective multiple of physical links, determining that the requested bandwidth is not satisfied by any of the number of remaining bandwidths of the number of physical links, and sending a response rejecting the request to establish the path.

TECHNICAL FIELD

The present disclosure relates generally to a field of datacommunications, and more particularly, to bandwidth awareness in a linkaggregation group.

BACKGROUND

With emerging IP Fabric for Media, content providers and broadcastersmay be able to migrate from legacy Serial Digital Interface (SDI) to anIP-based infrastructure. The IP-based infrastructure may be flexible andscalable to meet the evolving demand for more content and rich mediaexperiences, including, but not limited to, more camera feeds, higherresolutions, and virtual reality capabilities. Media traffic may beprovided as multicast streams in the IP-based infrastructure. Linkaggregation may be used for increasing the bandwidth available betweennetwork nodes in the IP-based infrastructure, especially for IP Fabricfor Media. Traffic in IP Fabric for Media may requireguaranteed-bandwidth infrastructure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example link aggregation between two switches.

FIG. 2 illustrates an example architecture for delivering a multicastservice.

FIG. 3A illustrates an example scenario where two network apparatusesare connected by a link aggregation group.

FIG. 3B illustrates an example scenario where a path for a first datastream over the link aggregation group is established.

FIG. 3C illustrates an example scenario where a physical link in a linkaggregation group fails.

FIG. 3D illustrates another example scenario where a physical link in alink aggregation group fails.

FIG. 4 illustrates an example method for processing a request toestablish a path over a link aggregation group for aguaranteed-bandwidth data stream.

FIG. 5 illustrates an example method for requesting to establish a pathover a link aggregation group for a guaranteed-bandwidth data stream.

FIG. 6 illustrates an example computer system.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

In particular embodiments, a first network apparatus may receive a firstrequest to establish a first path for a first data stream from the firstnetwork apparatus to a second network apparatus. The first request maybe associated with a first requested bandwidth for the first datastream. The first network apparatus and the second network apparatus maybe connected by a link aggregation group comprising a plurality ofphysical links. The first network apparatus may access bandwidthinformation representing a plurality of remaining bandwidths of therespective plurality of physical links. The first network apparatus maydetermine that the first requested bandwidth is not satisfied by any ofthe plurality of remaining bandwidths of the plurality of physicallinks. The first network apparatus may send a response rejecting thefirst request to establish the first path based on the determination.

In particular embodiments, a second network apparatus may identify afirst network apparatus from which to receive a data stream. The firstnetwork apparatus and the second network apparatus are connected by alink aggregation group comprising a plurality of physical links. Thesecond network apparatus may access bandwidth information associatedwith the link aggregation group. The second network apparatus maydetermine that a remaining ingress bandwidth associated with the linkaggregation group satisfies a requested bandwidth for receiving the datastream based on the bandwidth information. The second network apparatusmay send a request for establishing a first path between the firstnetwork apparatus to the second network apparatus with the requestedbandwidth to the first network apparatus.

Example Embodiments

Link aggregation may address two problems with Ethernet connections:bandwidth limitations and lack of resilience. With regard to the firstissue: bandwidth requirements may not scale linearly. Ethernetbandwidths historically have increased tenfold each generation: 10megabit/s, 100 Mbit/s, 1000 Mbit/s, 10,000 Mbit/s. Upgrading to the nextgeneration to increase bandwidth of a link may be cost prohibitive. Thesecond problem may involve the three single points of failure in atypical port-cable-port connection. In either the usualcomputer-to-switch or in a switch-to-switch configuration, the cableitself or either of the ports the cable is plugged into can fail. Linkaggregation may combine (aggregate) multiple network connections inparallel in order to increase throughput beyond what a single connectioncould sustain, and to provide redundancy in case one of the links shouldfail. A Link Aggregation Group (LAG) may combine a number of physicalports together to make a single high-bandwidth data path, so as toimplement the traffic load sharing among the member ports in the groupand to enhance the connection reliability. EtherChannel may be aproprietary link aggregation solution from CISCO®. EtherChannel mayallow grouping of several physical Ethernet links to create one logicalEthernet link for the purpose of providing fault-tolerance andhigh-speed links between switches, routers and servers. EtherChannel maybe primarily used in a backbone network. But, EtherChannel can also beused to connect end user machines. FIG. 1 illustrates an example linkaggregation between two switches. Switch A 110 has a connection toswitch B 120 with link aggregation. Port-1 111 of switch A 110 has aconnected link to port-1 121 of switch B 120. Port-2 112 of switch B 110has a connected link to the port-2 122 of switch B1 120. The two linksbetween switch A and switch B may be aggregated to form a logical layer2 link. With the aggregated link, the data bandwidth between switch Aand switch B may become higher. Also, the connection reliability mayincrease as the connection between switch A and switch B may exist evenif one of the physical links fails.

Internet Group Management Protocol (IGMP) is a communications protocolused by hosts and adjacent routers on Internet Protocol Version 4 (IPv4)networks to establish multicast group memberships. IGMP may be used forone-to-many networking applications such as online streaming video andgaming. IGMP may allow more efficient use of resources when supportingthese types of applications. IGMP may be used on IPv4 networks.Multicast management on IPv6 networks may be handled by MulticastListener Discovery (MLD) which is a part of ICMPv6 in contrast to IGMP'sbare IP encapsulation.

FIG. 2 illustrates an example architecture for delivering a multicastservice. IGMP may operate between a client host 213 and a localmulticast router 225. Switches 223 featuring IGMP snooping may deriveuseful information by observing these IGMP transactions. ProtocolIndependent Multicast (PIM) is then used between the local multicastrouter 225 and remote multicast routers 227, to direct multicast trafficfrom a server host 215 sending multicasts to hosts that have registeredthrough IGMP to receive them. IGMP may operate on the network layer.IGMP protocol may be implemented on a particular host and within arouter. A client host 213 may request membership to a group through thelocal multicast router 225 while the local multicast router 225 maylisten for these requests and periodically sends out subscriptionqueries. A single router per subnet may be elected to perform thisquerying function.

Protocol Independent Multicast (PIM) is a family of multicast routingprotocols for Internet Protocol (IP) networks that provide one-to-manyand many-to-many distribution of data over a Local Area Network (LAN),Wide Area Network (WAN) or the Internet. PIM may not include its owntopology discovery mechanism, but instead may use routing informationsupplied by other routing protocols. PIM may not be dependent on aspecific unicast routing protocol: PIM can make use of any unicastrouting protocol in use on the network. PIM may not build its ownrouting tables. PIM may use the unicast routing table for reverse pathforwarding.

FIG. 3A-FIG. 3D illustrate example scenarios of establishing a path overa link aggregation group for guaranteed-bandwidth data streams.

In particular embodiments, a first network apparatus and the secondnetwork apparatus may be connected by a link aggregation groupcomprising a plurality of physical links. FIG. 3A illustrates an examplescenario where two network apparatuses are connected by a linkaggregation group. As an example and not by way of limitation,illustrated in FIG. 3A, Spine-B 340, the first network apparatus, isconnected to Leaf-3 330, the second network apparatus, by a linkaggregation group 370. The link aggregation group 370 may comprise threephysical links L1 371, L2 372, and L3 373. A directional capacity ofeach physical link in the link aggregation group 370 may be 4 Gbps. Thelink aggregation group may be an EtherChannel of CISCO®. Although thisdisclosure describes two network apparatuses connected by a linkaggregation group in a particular manner, this disclosure contemplatestwo network apparatuses connected by a link aggregation group in anysuitable manner.

In particular embodiments, the first network apparatus 340 may manage anegress bandwidth table 343 for the link aggregation group 370. Theegress bandwidth table 343 may comprise a total bandwidth, a usedbandwidth, and a remaining bandwidth for each of the plurality ofphysical links. Each of the plurality of physical links may beassociated with zero or more streams. The total bandwidth for a physicallink may be an egress capacity of the physical link. The used bandwidthfor a physical link may be a sum of required egress bandwidth for thezero or more streams associated with the physical link. The remainingbandwidth for a physical link may be calculated as a subtraction of theused bandwidth from the total bandwidth. As an example and not by way oflimitation, illustrated in FIG. 3A, the egress bandwidth table 343 forSpine-B 340 comprises the total bandwidth, the used bandwidth, and theremaining bandwidth for interfaces E1/1, E1/2, E1/3, where the interfaceE1/1 is connected to the link L1 371, the interface E1/2 is connected tothe link L2 372, and the interface E1/3 is connected to the link L3.Because the capacity of each link in the link aggregation group 370 is 4Gbps, the total bandwidth for each interface E1/1, E1/2, and E1/3 is 4Gbps. In the example illustrated in FIG. 3A, each of the links L1 and L2is utilized by one or more egress streams while the link L3 is notassociated with any egress stream. Total required egress bandwidth forthe one or more streams associated with L1 is 3 Gbps. Thus, the usedbandwidth for interface E1/1 in the egress bandwidth table 343 is 3Gbps. Total required egress bandwidth for the one or more streamsassociated with L2 is 3 Gbps. Thus, the used bandwidth for interfaceE1/2 in the egress bandwidth table 343 is 3 Gbps. Although thisdisclosure describes managing egress bandwidth information per link in alink aggregation group in a particular manner, this disclosurecontemplates managing egress bandwidth information per link in a linkaggregation group in any suitable manner.

In particular embodiments, the first network apparatus may update thebandwidth information for the link aggregation group when an associationof a stream to a physical link is created, removed, or modified. Thebandwidth information associated with each of the plurality of physicallinks is updated based on any egress bandwidth allocated to any streamutilizing that physical link. Although this disclosure describesupdating the bandwidth information for a link aggregation group in aparticular manner, this disclosure contemplates updating the bandwidthinformation for a link aggregation group in any suitable manner.

In particular embodiments, the second network apparatus 330 may managean ingress bandwidth table 333 for the link aggregation group 370. Theingress bandwidth table 333 may comprise a total ingress bandwidth, aused ingress bandwidth, and a remaining ingress bandwidth for the wholelink aggregation group. The total ingress bandwidth may be anaggregation of ingress capacities of the plurality of physical links.The used ingress bandwidth may be a sum of required ingress bandwidthfor zero or more streams associated with the link aggregation group. Theremaining ingress bandwidth may be calculated as a subtraction of theused bandwidth from the total bandwidth. As an example and not by way oflimitation, illustrated in FIG. 3A, the aggregation of ingresscapacities of the links L1 371, L2 372 and L3 373 is 12 Gbps. Thus, thetotal ingress bandwidth in the ingress bandwidth table 333 is 12 Gbps.Because 3 Gbps is required for the one or more streams associated withthe link L1 371 and 3 Gbps is required for the one or more streamsassociated with the link L2 372, the total used ingress bandwidth forthe link aggregation group 370 at leaf-3 330 is 6 Gbps. As a result, theremaining ingress bandwidth for the link aggregations group 370 atLeaf-3 330 is 6 Gbps. Although this disclosure describes managing aningress bandwidth information in a particular manner, this disclosurecontemplates managing an ingress bandwidth information in any suitablemanner.

In particular embodiments, the one or more streams associated with aphysical link may be hashed into the physical link. The one or morestreams associated with a physical link may be transmitted through thephysical link. As an example and not by way of limitation, illustratedin FIG. 3A, the link L1 371 is associated with a stream that requires 3Gbps. The stream is hashed into the interface E1/1, the interfaceconnected to the link L1 371. Whenever a packet belonging to the streamarrives to Spine-B 340, the packet is sent to Leaf-3 330 through thelink L1. Although this disclosure describes associating a stream to aphysical link in a particular manner, this disclosure contemplatesassociating a stream to a physical link in any suitable manner.

In particular embodiments, a second network apparatus 330 may receive,from a client node, a first request to establish a first-routing pathfor a first data stream. In particular embodiments, the first datastream may be a multicast stream. In particular embodiments, the firstrequest may be an IGMP join message requesting to join to a multicastgroup. The first request may be associated with a first requestedbandwidth for the first data stream. The second network apparatus 330may identify the first network apparatus 340 from which to receive thefirst data stream based on routing algorithms. In particularembodiments, the first network apparatus 340 may be a next networkapparatus in a reversed routing path based on reverse-path forwardingalgorithms. The second network apparatus 330 may access bandwidthinformation associated with the link aggregation group. The bandwidthinformation associated with the link aggregation group may be availableas an ingress bandwidth table 333. The second network apparatus 330 maydetermine that the remaining ingress bandwidth associated with the linkaggregation group satisfies a requested bandwidth for receiving the datastream based on the bandwidth information. The second network apparatus330 may send to the first network apparatus 340 a request forestablishing a first path between the first network apparatus to thesecond network apparatus with the requested bandwidth. As an example andnot by way of limitation, illustrated in FIG. 3A, a client-1 331 maywant to join to a multicast group G1 sourced from a server-1 311, whichbelongs to Leaf-1 310. The multicast stream associated with themulticast group G1 may require 3 Gbps bandwidth. Leaf-3 330 may receivean IGMP Join request from the client-1 331. The IGMP Join request maycomprise the requested bandwidth, 3 Gbps. Leaf-3 330 may perform aMulticast Reverse-Path Forwarding (M-RPF) lookup. Leaf-3 330 mayidentify Spine-B 340 as the next network apparatus in the reversedrouting path for the multicast stream based on the M-RPF lookup. BecauseLeaf-3 330 is connected to Spine-B 340 by a link aggregation group 370,Leaf-3 330 may determine if the remaining ingress bandwidth satisfiesthe requested bandwidth using the ingress bandwidth table 333. Since theremaining ingress bandwidth 6 Gbps is greater than the requestedbandwidth 3 Gbps for the multicast stream, Leaf-3 330 may send aProtocol Independent Multicast (PIM) Join request to Spine-B 340.Although this disclosure describes requesting to establish a path over alink aggregation group for a multicast stream in a particular manner,this disclosure contemplates requesting to establish a path over a linkaggregation group for a multicast stream in any suitable manner.

In particular embodiments, the first network apparatus 340 may receivethe request to establish a first path for the first data stream. Thefirst path may be between the first network apparatus 340 to the secondnetwork apparatus 330. The first network apparatus 340 and the secondnetwork apparatus 330 may be connected by a link aggregation group 370.The request may be associated with a first requested bandwidth. Thefirst network apparatus 340 may access the egress bandwidth informationassociated with the link aggregation group 370. The egress bandwidthinformation associated with the link aggregation group 370 may be theegress bandwidth table 343. The first network apparatus 340 maydetermine that the remaining bandwidth of one physical link among theplurality of physical links satisfies the second requested bandwidth.The first network apparatus may update the bandwidth informationassociated with the one physical link based on the second requestedbandwidth. As an example and not by way of limitation, illustrated inFIG. 3A, continuing with a prior example, Spine-B 340 may receive thePIM Join request from the second network apparatus 330. The received PIMJoin request may comprise the first requested bandwidth associated withthe first data stream. Spine-B 340 may determine that the remainingbandwidth of link L3 373 satisfies the first requested bandwidth.Spine-B 340 may add the first requested bandwidth, 3 Gbps, to the usedbandwidth of the interface E1/3, which is connected to the link L3.Spine-B 340 may subtract the first requested bandwidth 3 Gbps from theremaining bandwidth of the interface E1/3. Spine-B 340 may perform anM-RPF lookup to determine that Leaf-1 310 is a next network apparatus inthe reversed routing path. In particular embodiments, Spine-B 340 mayutilize any suitable multicast routing discovery algorithms to determinethe next network apparatus in the reversed routing path. The firstnetwork apparatus 340 may send a PIM Join request to Leaf-1 310.Although this disclosure describes establishing an egress path over alink aggregation group for a multicast stream in a particular manner,this disclosure contemplates establishing an egress path over a linkaggregation group for a multicast stream in any suitable manner.

In particular embodiments, the second network apparatus 330 may updatethe ingress bandwidth information for the link aggregation group 370.The bandwidth information associated with the link aggregation group 370may be the ingress bandwidth table 333. The bandwidth informationassociated with the link aggregation group 370 may be updated based onany ingress bandwidth allocated to any ingress stream over the linkaggregation group. In particular embodiments, the second networkapparatus 330 may update the ingress bandwidth information for the linkaggregation group 370 upon receiving a response indicating that therequest to establish a path over the link aggregation group is acceptedfrom the first network apparatus 340. As an example and not by way oflimitation, illustrated in FIG. 3A, continuing with a prior example,Leaf-3 330 may update the ingress bandwidth table 333 by adding thefirst requested bandwidth 3 Gbps to the used bandwidth and subtractingthe first requested bandwidth 3 Gbps from the remaining bandwidth.Although this disclosure describes updating the ingress bandwidthinformation for a link aggregation group in a particular manner, thisdisclosure contemplates updating the ingress bandwidth information for alink aggregation group in any suitable manner.

FIG. 3B illustrates an example scenario where a path for a first datastream over the link aggregation group is established. The used egressbandwidth for the interface E1/3 in the egress bandwidth table 343,connected to link L3, has been updated to 3 Gbps. The remaining egressbandwidth for the interface E1/3 in the egress bandwidth table 343 hasbeen updated to 1 Gbps. The used ingress bandwidth for the linkaggregation group 370 in the ingress bandwidth table 333 has beenupdated to 9 Gbps. The remaining ingress bandwidth for the linkaggregation group 370 in the ingress bandwidth table 333 has beenupdated to 3 Gbps.

In particular embodiments, a second network apparatus 330 may receive,from a client node, a second request to establish a second routing pathfor a second data stream. In particular embodiments, the second datastream may be a multicast stream. In particular embodiments, the secondrequest may be an IGMP join message requesting for joining to amulticast group. The second request may be associated with a secondrequested bandwidth for the second data stream. The second networkapparatus 330 may identify the first network apparatus 340 from which toreceive the second data stream based on routing algorithms. Inparticular embodiments, the first network apparatus 340 may be a nextnetwork apparatus in a reversed routing path based on reverse-pathforwarding algorithms. The second data stream may be delivered from asecond source node to a second destination node. The second source nodemay be reachable from the second network apparatus 340. The seconddestination node may be reachable from the second network apparatus 330.The second routing path may comprise a path from the second source nodeto the first network apparatus 340, a path from the first networkapparatus 340 to the second network apparatus 330, and a path from thesecond network apparatus 330 to the second destination node. The secondnetwork apparatus 330 may access bandwidth information associated withthe link aggregation group. The bandwidth information associated withthe link aggregation group may be available as an ingress bandwidthtable 333. The second network apparatus 330 may determine that theremaining ingress bandwidth associated with the link aggregation groupsatisfies the second requested bandwidth for receiving the data streambased on the bandwidth information. The second network apparatus 330 maysend to the first network apparatus 340 a request for establishing asecond path between the first network apparatus to the second networkapparatus with the requested bandwidth. In particular embodiments, thesecond network apparatus 330 may determine that the remaining ingressbandwidth associated with the link aggregation group does not satisfiesthe second requested bandwidth. In such a case, the second networkapparatus 330 may determine an alternative routing path to a source nodefor the second data stream based on routing algorithms. The secondnetwork apparatus 330 may send a request to establish the alternativerouting path for the second data stream to a next network apparatus inthe reversed alternative routing path. As an example and not by way oflimitation, illustrated in FIG. 3B, a client-2 332 may want to join to amulticast group G2 sourced from a server-2 322, which belongs to Leaf-2320. The multicast stream associated with the multicast group G2 mayrequire 2 Gbps bandwidth. Leaf-3 330 may receive an IGMP Join requestfrom the client-2 332. The IGMP Join request may comprise the requestedbandwidth, 2 Gbps. Leaf-3 330 may perform a Multicast Reverse-PathForwarding (M-RPF) lookup. Leaf-3 330 may identify Spine-B 340 as thenext network apparatus in the reversed routing path for the multicaststream based on the M-RPF lookup. Because Leaf-3 330 is connected toSpine-B 340 by a link aggregation group 370, Leaf-3 330 may determine ifthe remaining ingress bandwidth satisfies the requested bandwidth usingthe ingress bandwidth table 333. Since the remaining ingress bandwidth 3Gbps is greater than the requested bandwidth 2 Gbps for the multicaststream, Leaf-3 330 may send a Protocol Independent Multicast (PIM) Joinrequest to Spine-B 340. As another example and not by way of limitation,a client-2 332 may want to join to a multicast group G2 sourced from aserver-2 322, which belongs to Leaf-2 320. The multicast streamassociated with the multicast group G2 may require 4 Gbps bandwidth.Leaf-3 330 may receive an IGMP Join request from the client-2 332. TheIGMP Join request may comprise the requested bandwidth, 4 Gbps. Leaf-3330 may perform a Multicast Reverse-Path Forwarding (M-RPF) lookup.Leaf-3 330 may identify Spine-B 340 as the next network apparatus in thereversed routing path for the multicast stream based on the M-RPFlookup. The routing path for the multicast stream may comprise a pathfrom the server-2 322 to Spine-B 340, a path from Spine-B 340 to Leaf-3330, and a path from Leaf-3 330 to the client-2 332. Because Leaf-3 330is connected to Spine-B 340 by a link aggregation group 370, Leaf-3 330may determine if the remaining ingress bandwidth satisfies the requestedbandwidth using the ingress bandwidth table 333. Since the remainingingress bandwidth 3 Gbps is less than the requested bandwidth 4 Gbps forthe multicast stream, Leaf-3 330 may determine an alternative routingpath to the server-2 322, the source node for the multicast stream basedon routing algorithms. Leaf-3 330 may send a request to establish thealternative routing path for the second data stream to Spine-A 350, anext network apparatus in the reversed alternative routing path toSever-2 322. The request may be a PIM Join message. Although thisdisclosure describes requesting to establish a path over a linkaggregation group for a multicast stream in a particular manner, thisdisclosure contemplates requesting to establish a path over a linkaggregation group for a multicast stream in any suitable manner.

In particular embodiments, the first network apparatus 340 may receive asecond request to establish a second path for the second data stream.The second path may be from the first network apparatus 340 to thesecond network apparatus 330. The second request may be associated withthe second requested bandwidth for the second data stream. The firstnetwork apparatus 340 may access egress bandwidth informationrepresenting a plurality of remaining bandwidths of the respectiveplurality of physical links. The egress bandwidth information may be theegress bandwidth table 343. The first network apparatus 340 maydetermine that the second requested bandwidth is not satisfied by any ofthe plurality of remaining bandwidths of the plurality of physicallinks. To make the determination, the first network apparatus 340 maycompare the remaining bandwidth with the second requested bandwidth foreach of the plurality of physical links in the link aggregation group.As an example and not by way of limitation, illustrated in FIG. 3B,continuing with a prior example, Spine-B 340 may receive the PIM Joinmessage from Leaf-3 330. The PIM Join message may be associated with therequested bandwidth 2 Gbps. Because Spine-B 340 and Leaf-3 330 areconnected by a link aggregation group 370, Spine-B 340 may access theegress bandwidth table 343 to determine whether a remaining bandwidth ofany link in the link aggregation group 370 satisfies the requestedbandwidth. Currently, the remaining bandwidth for L1 371 is 1 Gbps, theremaining bandwidth for L2 372 is 1 Gbps, and the remaining bandwidthfor L3 373 is 1 Gbps. Though the aggregation of the remaining bandwidthsof all the links is greater than the requested bandwidth 2 Gbps, nosingle link has greater than or equal to the requested bandwidth 3 Gbps.Thus, Spine-B 340 may determine that the requested bandwidth 2 Gbpscannot be satisfied by any of the remaining bandwidth of link L1 371, L2372, and L3 373. Although this disclosure describes determining whetherthe requested bandwidth is satisfied by any of the plurality ofremaining bandwidths of the plurality of physical links in a particularmanner, this disclosure contemplates determining whether the requestedbandwidth is satisfied by any of the plurality of remaining bandwidthsof the plurality of physical links in any suitable manner.

The first network apparatus 340 may send, based on the determination, aresponse rejecting the second request to establish the second path. Theresponse rejecting the second request may cause the second networkapparatus 330 to choose an alternative routing path to the first sourcenode, wherein the alternative routing path does not comprise the secondpath from the first network apparatus 340 to the second networkapparatus 330. The response may be a PIM Equal-Cost Multipath (ECMP)Redirect. As an example and not by way of limitation, illustrated inFIG. 3B, continuing with a prior example, Spine-B 340 may send a PIMECPM redirect to Leaf-3 330 upon determining that the requestedbandwidth 2 Gbps cannot be satisfied by any of the remaining bandwidthof link L1 371, L2 372, and L3 373. Although this disclosure describessending a response rejecting a request to establish a path over a linkaggregation group for a Guaranteed-Bandwidth data stream in a particularmanner, this disclosure contemplates sending a response rejecting arequest to establish a path over a link aggregation group for aGuaranteed-Bandwidth data stream in any suitable manner.

The second network apparatus 330 may receive the response indicatingthat the second request is not accepted from the first network apparatus340. The second network apparatus 330 may determine an alternativerouting path to a source node for the data stream based on routingalgorithms. The second network apparatus 330 may send to a next networkapparatus in the reversed alternative routing path to the source nodefor the data stream, a request to establish the alternative routing pathfor the second data stream. As an example and not by way of limitation,illustrated in FIG. 3B, continuing with a prior example, Leaf-3 330 mayreceive a PIM ECMP Redirect from Spine-B 340. Leaf-3 330 may determinean alternative routing path to the server-2 322, the source node for themulticast stream based on routing algorithms. Leaf-3 330 may send arequest to establish the alternative routing path for the second datastream to Spine-A 350, a next network apparatus in the reversedalternative routing path to Sever-2 322. The request may be a PIM Joinmessage. Although this disclosure describes determining an alternativerouting path upon receiving a response rejecting the request toestablish a path in a particular manner, this disclosure contemplatesdetermining an alternative routing path upon receiving a responserejecting the request to establish a path in any suitable manner.

In particular embodiments, the first network apparatus 340 may detectthat the physical link i fails. The first network apparatus 340 maydetermine, for each data stream associated with the physical link i,whether an alternative physical link among the plurality of physicallinks can be utilized for the data stream based on the bandwidthinformation and the requested bandwidth associated with the data stream.The first network apparatus 340 may determine that no active physicallink among the plurality of physical links has the remaining bandwidththat satisfies the requested bandwidth for a data stream. In such acase, the first network apparatus 340 may send a message to a networkapparatus associated with the data stream to cause that networkapparatus to choose a new routing path. The message may be a PIM ECMPRedirect.

FIG. 3C illustrates an example scenario where a physical link in a linkaggregation group fails. As an example and not by way of limitation,illustrated in FIG. 3C, continuing with a prior example, the link L3 373in the link aggregation group 370 fails. The link L3 373 was associatedwith the first data stream from the server-1 311 to the client-1 331.The first requested bandwidth associated with the first data stream is 3Gbps. Upon detecting that the link L3 373 fails, Spine-B 340 maydetermine whether any link in the link aggregation group 370 can beutilized for the first data stream. The remaining bandwidth forinterface E1/1, connected to link L1 371, is 1 Gbps. The remainingbandwidth for interface E1/2, connected to link L2 372, is 1 Gbps.Because both of the remaining bandwidths for link L1 371 and L2 372 areless than the first requested bandwidth 3 Gbps, Spine-B determines thatthe first data stream cannot be delivered over the link aggregationgroup 370. Spine-B may send a PIM ECPM Redirect to Leaf-3 to causeLeaf-3 determine an alternative routing path for the first data stream.Although this disclosure describes determining that no alternativephysical link for a data stream associated with a failed physical linkis available in a link aggregation group in a particular manner, thisdisclosure contemplates determining that no alternative physical linkfor a data stream associated with a failed physical link is available ina link aggregation group in any suitable manner.

In particular embodiments, the second network apparatus 330 may receivea message indicating that the first data stream cannot be routed throughthe link between the first network apparatus and the second networkapparatus. The second network apparatus 330 may determine an alternativerouting path to a source node for the first data stream based on routingalgorithms. The second network apparatus 330 may send a request toestablish the alternative routing path for the first data stream to anext network apparatus in the reversed alternative routing path to thesource node for the first data stream. As an example and not by way oflimitation, illustrated in FIG. 3C, continuing with a prior example,Leaf-3 330 receives the PIM EC MP Redirect from Spine-B 340. Leaf-3 330may determine an alternative routing path to the server-1 311, thesource node for the first data stream based on routing algorithms.Leaf-3 330 may send a request to establish the alternative routing pathfor the second data stream to Spine-A 350, a next network apparatus inthe reversed alternative routing path to Server-1 311. The request maybe a PIM Join message. Although this disclosure describes determining analternative routing path due to a link failure in a particular manner,this disclosure contemplates determining an alternative routing path dueto a link failure in any suitable manner.

In particular embodiments, the first network apparatus 340 may detectthat the physical link i fails. The physical link i may be associatedwith a data stream. The data stream is associated with a requestedbandwidth. The first network apparatus 340 may determine, based on thebandwidth information and the requested bandwidth associated with thedata stream, whether an alternative physical link among the plurality ofphysical links can be used for the data stream. The first networkapparatus 340 may determine that the remaining bandwidth of a physicallink k among the plurality of physical links satisfies the requestedbandwidth. The first network apparatus may update the bandwidthinformation associated with the physical link k based on the requestedbandwidth. The data stream may be re-hashed into the physical link k.

FIG. 3D illustrates another example scenario where a physical link in alink aggregation group fails. As an example and not by way oflimitation, illustrated in FIG. 3D, the link L3 373 in the linkaggregation group 370 fails. The link L3 373 was associated with thefirst data stream from the server-1 311 to the client-1 331. The firstrequested bandwidth associated with the first data stream is 3 Gbps. Thelink L2 is currently associated with a second data stream. A requestedbandwidth associated with the second data stream is 1 Gbps. Thus, theremaining bandwidth of the link L2 is 3 Gbps. Upon detecting that thelink L1 fails, Spine-B 340 may determine that the remaining bandwidth ofthe link L2 satisfies the first requested bandwidth associated with thefirst data stream by accessing the egress bandwidth table 343. Spine-B340 may update the egress bandwidth table 343 by adding the firstrequested bandwidth 3 Gbps to the used bandwidth of the link L2 andsubtracting the first requested bandwidth 3 Gbps from the remainingbandwidth of the link L2. The first data stream may be re-hashed intothe link L2. Spine-B 340 does not send a message to Leaf-3, the ingressnetwork apparatus for the first data stream. Although this disclosuredescribes determining an alternative physical link in a link aggregationgroup due to a link failure in a particular manner, this disclosurecontemplates determining an alternative physical link in a linkaggregation group due to a link failure in any suitable manner.

In particular embodiments, one or more physical links may be added to alink aggregation group 370. A link addition (or a deletion) to a linkaggregation group may cause hash values for the data streams associatedwith the link aggregation group changed. Then, the data streams mayexperience service disruptions. The first network apparatus 340 may notchange the hash values for the data streams associated with the linkaggregation group when one or more physical links are added to a linkaggregation group 370 to prevent service disruptions on the data streamsfrom happening. Although this disclosure describes preventing servicedisruptions on the data streams associated with a link aggregation groupwhen one or more links are added to the link aggregation group in aparticular manner, this disclosure contemplates preventing servicedisruptions on the data streams associated with a link aggregation groupwhen one or more links are added to the link aggregation group in anysuitable manner.

FIG. 4 illustrates an example method 400 for processing a request toestablish a path over a link aggregation group for aguaranteed-bandwidth data stream. The method may begin at step 410,where the first network apparatus may receive a first request toestablish a first path for a first data stream from the first networkapparatus to a second network apparatus. The first request may beassociated with a first requested bandwidth for the first data stream.The first network apparatus and the second network apparatus may beconnected by a link aggregation group comprising a plurality of physicallinks. At step 420, the first network apparatus may access bandwidthinformation representing a plurality of remaining bandwidths of therespective plurality of physical links. At step 430, the first networkapparatus may determine that the first requested bandwidth is notsatisfied by any of the plurality of remaining bandwidths of theplurality of physical links. At step 440, the first network apparatusmay send a response rejecting the first request to establish the firstpath based on the determination. Particular embodiments may repeat oneor more steps of the method of FIG. 4, where appropriate. Although thisdisclosure describes and illustrates particular steps of the method ofFIG. 4 as occurring in a particular order, this disclosure contemplatesany suitable steps of the method of FIG. 4 occurring in any suitableorder. Moreover, although this disclosure describes and illustrates anexample method for processing a request to establish a path over a linkaggregation group for a guaranteed-bandwidth data stream including theparticular steps of the method of FIG. 4, this disclosure contemplatesany suitable method for processing a request to establish a path over alink aggregation group for a guaranteed-bandwidth data stream includingany suitable steps, which may include all, some, or none of the steps ofthe method of FIG. 4, where appropriate. Furthermore, although thisdisclosure describes and illustrates particular components, devices, orsystems carrying out particular steps of the method of FIG. 4, thisdisclosure contemplates any suitable combination of any suitablecomponents, devices, or systems carrying out any suitable steps of themethod of FIG. 4.

FIG. 5 illustrates an example method 500 for requesting to establish apath over a link aggregation group for a guaranteed-bandwidth datastream. The method may begin at step 510, where the second networkapparatus may identify a first network apparatus from which to receive adata stream, wherein the first network apparatus and the second networkapparatus are connected by a link aggregation group comprising aplurality of physical links. At step 520, the second network apparatusmay access bandwidth information associated with the link aggregationgroup. At step 530, the second network apparatus may determine that aremaining ingress bandwidth associated with the link aggregation groupsatisfies a requested bandwidth for receiving the data stream based onthe bandwidth information. At step 540, the second network apparatus maysend a request for establishing a first path between the first networkapparatus to the second network apparatus with the requested bandwidthto the first network apparatus. Particular embodiments may repeat one ormore steps of the method of FIG. 5, where appropriate. Although thisdisclosure describes and illustrates particular steps of the method ofFIG. 5 as occurring in a particular order, this disclosure contemplatesany suitable steps of the method of FIG. 5 occurring in any suitableorder. Moreover, although this disclosure describes and illustrates anexample method for requesting to establish a path over a linkaggregation group for a guaranteed-bandwidth data stream including theparticular steps of the method of FIG. 5, this disclosure contemplatesany suitable method for requesting to establish a path over a linkaggregation group for a guaranteed-bandwidth data stream including anysuitable steps, which may include all, some, or none of the steps of themethod of FIG. 5, where appropriate. Furthermore, although thisdisclosure describes and illustrates particular components, devices, orsystems carrying out particular steps of the method of FIG. 5, thisdisclosure contemplates any suitable combination of any suitablecomponents, devices, or systems carrying out any suitable steps of themethod of FIG. 5.

FIG. 6 illustrates an example computer system 600. In particularembodiments, one or more computer systems 600 perform one or more stepsof one or more methods described or illustrated herein. In particularembodiments, one or more computer systems 600 provide functionalitydescribed or illustrated herein. In particular embodiments, softwarerunning on one or more computer systems 600 performs one or more stepsof one or more methods described or illustrated herein or providesfunctionality described or illustrated herein. Particular embodimentsinclude one or more portions of one or more computer systems 600.Herein, reference to a computer system may encompass a computing device,and vice versa, where appropriate. Moreover, reference to a computersystem may encompass one or more computer systems, where appropriate.

This disclosure contemplates any suitable number of computer systems600. This disclosure contemplates computer system 600 taking anysuitable physical form. As example and not by way of limitation,computer system 600 may be an embedded computer system, a system-on-chip(SOC), a single-board computer system (SBC) (such as, for example, acomputer-on-module (COM) or system-on-module (SOM)), a desktop computersystem, a laptop or notebook computer system, an interactive kiosk, amainframe, a mesh of computer systems, a mobile telephone, a personaldigital assistant (PDA), a server, a tablet computer system, anaugmented/virtual reality device, or a combination of two or more ofthese. Where appropriate, computer system 600 may include one or morecomputer systems 600; be unitary or distributed; span multiplelocations; span multiple machines; span multiple data centers; or residein a cloud, which may include one or more cloud components in one ormore networks. Where appropriate, one or more computer systems 600 mayperform without substantial spatial or temporal limitation one or moresteps of one or more methods described or illustrated herein. As anexample and not by way of limitation, one or more computer systems 600may perform in real time or in batch mode one or more steps of one ormore methods described or illustrated herein. One or more computersystems 600 may perform at different times or at different locations oneor more steps of one or more methods described or illustrated herein,where appropriate.

In particular embodiments, computer system 600 includes a processor 602,memory 604, storage 606, an input/output (I/O) interface 608, acommunication interface 610, and a bus 612. Although this disclosuredescribes and illustrates a particular computer system having aparticular number of particular components in a particular arrangement,this disclosure contemplates any suitable computer system having anysuitable number of any suitable components in any suitable arrangement.

In particular embodiments, processor 602 includes hardware for executinginstructions, such as those making up a computer program. As an exampleand not by way of limitation, to execute instructions, processor 602 mayretrieve (or fetch) the instructions from an internal register, aninternal cache, memory 604, or storage 606; decode and execute them; andthen write one or more results to an internal register, an internalcache, memory 604, or storage 606. In particular embodiments, processor602 may include one or more internal caches for data, instructions, oraddresses. This disclosure contemplates processor 602 including anysuitable number of any suitable internal caches, where appropriate. Asan example and not by way of limitation, processor 602 may include oneor more instruction caches, one or more data caches, and one or moretranslation lookaside buffers (TLBs). Instructions in the instructioncaches may be copies of instructions in memory 604 or storage 606, andthe instruction caches may speed up retrieval of those instructions byprocessor 602. Data in the data caches may be copies of data in memory604 or storage 606 for instructions executing at processor 602 tooperate on; the results of previous instructions executed at processor602 for access by subsequent instructions executing at processor 602 orfor writing to memory 604 or storage 606; or other suitable data. Thedata caches may speed up read or write operations by processor 602. TheTLBs may speed up virtual-address translation for processor 602. Inparticular embodiments, processor 602 may include one or more internalregisters for data, instructions, or addresses. This disclosurecontemplates processor 602 including any suitable number of any suitableinternal registers, where appropriate. Where appropriate, processor 602may include one or more arithmetic logic units (ALUs); be a multi-coreprocessor; or include one or more processors 602. Although thisdisclosure describes and illustrates a particular processor, thisdisclosure contemplates any suitable processor.

In particular embodiments, memory 604 includes main memory for storinginstructions for processor 602 to execute or data for processor 602 tooperate on. As an example and not by way of limitation, computer system600 may load instructions from storage 606 or another source (such as,for example, another computer system 600) to memory 604. Processor 602may then load the instructions from memory 604 to an internal registeror internal cache. To execute the instructions, processor 602 mayretrieve the instructions from the internal register or internal cacheand decode them. During or after execution of the instructions,processor 602 may write one or more results (which may be intermediateor final results) to the internal register or internal cache. Processor602 may then write one or more of those results to memory 604. Inparticular embodiments, processor 602 executes only instructions in oneor more internal registers or internal caches or in memory 604 (asopposed to storage 606 or elsewhere) and operates only on data in one ormore internal registers or internal caches or in memory 604 (as opposedto storage 606 or elsewhere). One or more memory buses (which may eachinclude an address bus and a data bus) may couple processor 602 tomemory 604. Bus 612 may include one or more memory buses, as describedbelow. In particular embodiments, one or more memory management units(MMUs) reside between processor 602 and memory 604 and facilitateaccesses to memory 604 requested by processor 602. In particularembodiments, memory 604 includes random access memory (RAM). This RAMmay be volatile memory, where appropriate. Where appropriate, this RAMmay be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, whereappropriate, this RAM may be single-ported or multi-ported RAM. Thisdisclosure contemplates any suitable RAM. Memory 604 may include one ormore memories 604, where appropriate. Although this disclosure describesand illustrates particular memory, this disclosure contemplates anysuitable memory.

In particular embodiments, storage 606 includes mass storage for data orinstructions. As an example and not by way of limitation, storage 606may include a hard disk drive (HDD), a floppy disk drive, flash memory,an optical disc, a magneto-optical disc, magnetic tape, or a UniversalSerial Bus (USB) drive or a combination of two or more of these. Storage606 may include removable or non-removable (or fixed) media, whereappropriate. Storage 606 may be internal or external to computer system600, where appropriate. In particular embodiments, storage 606 isnon-volatile, solid-state memory. In particular embodiments, storage 606includes read-only memory (ROM). Where appropriate, this ROM may bemask-programmed ROM, programmable ROM (PROM), erasable PROM (EPROM),electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM),or flash memory or a combination of two or more of these. Thisdisclosure contemplates mass storage 606 taking any suitable physicalform. Storage 606 may include one or more storage control unitsfacilitating communication between processor 602 and storage 606, whereappropriate. Where appropriate, storage 606 may include one or morestorages 606. Although this disclosure describes and illustratesparticular storage, this disclosure contemplates any suitable storage.

In particular embodiments, I/O interface 608 includes hardware,software, or both, providing one or more interfaces for communicationbetween computer system 600 and one or more I/O devices. Computer system600 may include one or more of these I/O devices, where appropriate. Oneor more of these I/O devices may enable communication between a personand computer system 600. As an example and not by way of limitation, anI/O device may include a keyboard, keypad, microphone, monitor, mouse,printer, scanner, speaker, still camera, stylus, tablet, touch screen,trackball, video camera, another suitable I/O device or a combination oftwo or more of these. An I/O device may include one or more sensors.This disclosure contemplates any suitable I/O devices and any suitableI/O interfaces 608 for them. Where appropriate, I/O interface 608 mayinclude one or more device or software drivers enabling processor 602 todrive one or more of these I/O devices. I/O interface 608 may includeone or more I/O interfaces 608, where appropriate. Although thisdisclosure describes and illustrates a particular I/O interface, thisdisclosure contemplates any suitable I/O interface.

In particular embodiments, communication interface 610 includeshardware, software, or both providing one or more interfaces forcommunication (such as, for example, packet-based communication) betweencomputer system 600 and one or more other computer systems 600 or one ormore networks. As an example and not by way of limitation, communicationinterface 610 may include a network interface controller (NIC) ornetwork adapter for communicating with an Ethernet or other wire-basednetwork or a wireless NIC (WNIC) or wireless adapter for communicatingwith a wireless network, such as a WI-FI network. This disclosurecontemplates any suitable network and any suitable communicationinterface 610 for it. As an example and not by way of limitation,computer system 600 may communicate with an ad hoc network, a personalarea network (PAN), a local area network (LAN), a wide area network(WAN), a metropolitan area network (MAN), or one or more portions of theInternet or a combination of two or more of these. One or more portionsof one or more of these networks may be wired or wireless. As anexample, computer system 600 may communicate with a wireless PAN (WPAN)(such as, for example, a BLUETOOTH WPAN), a WI-FI network, a WI-MAXnetwork, a cellular telephone network (such as, for example, a GlobalSystem for Mobile Communications (GSM) network), or other suitablewireless network or a combination of two or more of these. Computersystem 600 may include any suitable communication interface 610 for anyof these networks, where appropriate. Communication interface 610 mayinclude one or more communication interfaces 610, where appropriate.Although this disclosure describes and illustrates a particularcommunication interface, this disclosure contemplates any suitablecommunication interface.

In particular embodiments, bus 612 includes hardware, software, or bothcoupling components of computer system 600 to each other. As an exampleand not by way of limitation, bus 612 may include an AcceleratedGraphics Port (AGP) or other graphics bus, an Enhanced Industry StandardArchitecture (EISA) bus, a front-side bus (FSB), a HYPERTRANSPORT (HT)interconnect, an Industry Standard Architecture (ISA) bus, an INFINIBANDinterconnect, a low-pin-count (LPC) bus, a memory bus, a Micro ChannelArchitecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, aPCI-Express (PCIe) bus, a serial advanced technology attachment (SATA)bus, a Video Electronics Standards Association local (VLB) bus, oranother suitable bus or a combination of two or more of these. Bus 612may include one or more buses 612, where appropriate. Although thisdisclosure describes and illustrates a particular bus, this disclosurecontemplates any suitable bus or interconnect.

Herein, a computer-readable non-transitory storage medium or media mayinclude one or more semiconductor-based or other integrated circuits(ICs) (such, as for example, field-programmable gate arrays (FPGAs) orapplication-specific ICs (ASICs)), hard disk drives (HDDs), hybrid harddrives (HHDs), optical discs, optical disc drives (ODDs),magneto-optical discs, magneto-optical drives, floppy diskettes, floppydisk drives (FDDs), magnetic tapes, solid-state drives (SSDs),RAM-drives, SECURE DIGITAL cards or drives, any other suitablecomputer-readable non-transitory storage media, or any suitablecombination of two or more of these, where appropriate. Acomputer-readable non-transitory storage medium may be volatile,non-volatile, or a combination of volatile and non-volatile, whereappropriate.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

The scope of this disclosure encompasses all changes, substitutions,variations, alterations, and modifications to the example embodimentsdescribed or illustrated herein that a person having ordinary skill inthe art would comprehend. The scope of this disclosure is not limited tothe example embodiments described or illustrated herein. Moreover,although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,feature, functions, operations, or steps, any of these embodiments mayinclude any combination or permutation of any of the components,elements, features, functions, operations, or steps described orillustrated anywhere herein that a person having ordinary skill in theart would comprehend. Furthermore, reference in the appended claims toan apparatus or system or a component of an apparatus or system beingadapted to, arranged to, capable of, configured to, enabled to, operableto, or operative to perform a particular function encompasses thatapparatus, system, component, whether or not it or that particularfunction is activated, turned on, or unlocked, as long as thatapparatus, system, or component is so adapted, arranged, capable,configured, enabled, operable, or operative. Additionally, although thisdisclosure describes or illustrates particular embodiments as providingparticular advantages, particular embodiments may provide none, some, orall of these advantages.

What is claimed is:
 1. A first network apparatus, comprising: one ormore processors; and one or more computer-readable non-transitorystorage media coupled to the one or more processors and comprisinginstructions operable when executed by the one or more processors tocause the first network apparatus to: receive a first request toestablish a first path for a first data stream from the first networkapparatus to a second network apparatus, wherein the first request isassociated with a first requested bandwidth for the first data stream,and wherein the first network apparatus and the second network apparatusare connected by a link aggregation group comprising a plurality ofphysical links; access bandwidth information representing a plurality ofremaining bandwidths of the respective plurality of physical links;determine that the first requested bandwidth is not satisfied by any ofthe plurality of remaining bandwidths of the plurality of physicallinks; and send, based on the determination, a response rejecting thefirst request to establish the first path.
 2. The first networkapparatus of claim 1, wherein the first data stream is delivered from afirst source apparatus to a first destination apparatus, wherein thefirst source apparatus is reachable from the first network apparatus,and wherein the second destination apparatus is reachable from thesecond network apparatus.
 3. The first network apparatus of claim 2,wherein the response rejecting the first request causes the secondnetwork apparatus to choose an alternative routing path to the firstsource apparatus, wherein the alternative routing path does not comprisethe first path.
 4. The first network apparatus of claim 1, wherein thefirst data stream is a multicast stream, and wherein the first requestto establish the first path is a request to join to a multicast group.5. The first network apparatus of claim 1, wherein the one or moreprocessors are further operable when executing the instructions toupdate the bandwidth information for the link aggregation group, whereinthe bandwidth information associated with each of the plurality ofphysical links is updated based on any egress bandwidth allocated to anystream utilizing that physical link.
 6. The first network apparatus ofclaim 1, wherein the one or more processors are further operable whenexecuting the instructions to: receive a second request to establish asecond path for a second data stream, wherein the second request isassociated with a second requested bandwidth; determine that theremaining bandwidth of a physical link i among the plurality of physicallinks satisfies the second requested bandwidth; and update the bandwidthinformation associated with the physical link i based on the secondrequested bandwidth.
 7. The first network apparatus of claim 6, whereinthe one or more processors are further operable when executing theinstructions to: detect that the physical link i fails; and determine,based on the bandwidth information and the second requested bandwidth,whether an alternative physical link among the plurality of physicallinks can be used for the second path.
 8. The first network apparatus ofclaim 7, wherein the one or more processors are further operable whenexecuting the instructions to: determine that the remaining bandwidth ofa physical link k among the plurality of physical links satisfies thesecond requested bandwidth; update the bandwidth information associatedwith the physical link k based on the second requested bandwidth.
 9. Thefirst network apparatus of claim 7, wherein the one or more processorsare further operable when executing the instructions to: determine thatno active physical link among the plurality of physical links has theremaining bandwidth that satisfies the second requested bandwidth; andsend a message to a network apparatus associated with the second requestto cause that network apparatus to choose a new routing path.
 10. Asecond network apparatus, comprising: one or more processors; and one ormore computer-readable non-transitory storage media coupled to the oneor more processors and comprising instructions operable when executed bythe one or more processors to cause the second network apparatus to:identify a first network apparatus from which to receive a data stream,wherein the first network apparatus and the second network apparatus areconnected by a link aggregation group comprising a plurality of physicallinks; access bandwidth information associated with the link aggregationgroup; determine, based on the bandwidth information, that a remainingingress bandwidth associated with the link aggregation group satisfies arequested bandwidth for receiving the data stream; and send, to thefirst network apparatus, a request for establishing a first path betweenthe first network apparatus to the second network apparatus with therequested bandwidth.
 11. The second network apparatus of claim 10,wherein the one or more processors are further operable when executingthe instructions to update the bandwidth information for the linkaggregation group, wherein the bandwidth information associated with thelink aggregation group is updated based on any ingress bandwidthallocated to any ingress stream over the link aggregation group.
 12. Thesecond network apparatus of claim 10, wherein the one or more processorsare further operable when executing the instructions to: receive, fromthe first network apparatus, a response indicating the request isrejected; determine an alternative routing path to a source apparatusfor the data stream based on routing algorithms; and send to a nextnetwork apparatus in the reversed alternative routing path to the sourceapparatus for the data stream, a request to establish the alternativerouting path for the first multimedia stream.
 13. A method by a firstnetwork apparatus, comprising: receiving a first request to establish afirst path for a first data stream from the first network apparatus to asecond network apparatus, wherein the first request is associated with afirst requested bandwidth for the data transmission, wherein the firstnetwork apparatus and the second network apparatus are connected by alink aggregation group comprising a plurality of physical links;accessing bandwidth information representing a plurality of remainingbandwidths of the respective plurality of physical links; determiningthat the first requested bandwidth is not satisfied by any of theplurality of remaining bandwidths of the plurality of physical links;and sending, based on the determination, a response rejecting the firstrequest to establish the first path.
 14. The method of claim 13, whereinthe first data stream is delivered from a first source node to a firstdestination node, wherein the first source node is reachable from thefirst network apparatus, and wherein the second destination node isreachable from the second network apparatus.
 15. The method of claim 14,wherein the response rejecting the first request causes the secondnetwork apparatus to choose an alternative routing path to the firstsource node, wherein the alternative routing path does not comprise thefirst path.
 16. The method of claim 13, wherein the first data stream isa multicast stream, and wherein the first request to establish the firstpath is a request to join to a multicast group.
 17. The method of claim13, further comprising updating the bandwidth information for the linkaggregation group, wherein the bandwidth information associated witheach of the plurality of physical links is updated based on any egressbandwidth allocated to any stream utilizing that physical link.
 18. Themethod of claim 13, further comprising: receiving a second request toestablish a second path for a second data stream, wherein the secondrequest is associated with a second requested bandwidth; determiningthat the remaining bandwidth of a physical link i among the plurality ofphysical links satisfies the second requested bandwidth; and updatingthe bandwidth information associated with the physical link i based onthe second requested bandwidth.
 19. The method of claim 18, furthercomprising: detecting that the physical link i fails; and determining,based on the bandwidth information and the second requested bandwidth,whether an alternative physical link among the plurality of physicallinks can be used for the second path.
 20. The method of claim 19,further comprising determining that the remaining bandwidth of aphysical link k among the plurality of physical links satisfies thesecond requested bandwidth; updating the bandwidth informationassociated with the physical link k based on the second requestedbandwidth.